Wax coatings containing synergistic antioxidants



3' tions by rolling or brushing a liquid on one or both surfaces of wrapping materials and immediately driving olf excess water or other liquid solvents. Although both BHA and BHT antioxidants are quite soluble in various fats, oils, alcohols and other organic solvents, they are practically insoluble in water. Fats, oils, alcohols and various other organic solvents are not practical as solvents for the application ofpBl-IA or BHT to paper or other related wrapping materials ,for any,of several reasons which include the following: (1) the effect which suchsolvents have on thetexture of the'paper or similar wrapping' material, (2) the danger of re caused by some of the more volatile alcohols and organic solvents, an'd (3) the toxicity to humans of many of these materials. Because` of these limitations, as well as because of the economical factor involved, the most Vpractical carrier for the antioxidant combination with Which'this invention is concerned is water except where the paper or other packaging base material is to be coated with a hydrocarbon wax composition as described above. rIhe 'use of water as a carrier is accomplished throughthe preparationV of an emulsion of the antioxidant combination in'water.

t It is not ordinarily practicable to formulate an emulv sion at the spot where the application of the'emulsion to thepackaging material is to be accomplished. Therefore, this invention provides a meansfor formulating a concentrated emulsion which canbe transported to the place where the application to packaging materials is to be performed. The emulsionV can then be diluted to Athe proper strength and applied to the packaging material. Itis therefore necessary that Such an emulsion be stable stearate, various glyceride emulsitiers produced by nu- The solvent, di-isobutyl.adipate, was first heated to a temperature of 140 .F. A quantity of BHA pellets in both concentrated form as well as when greatly diluted. 1

According to this specific embodiment of this invention the applicants have provided an emulsion of the 'antioxidant combination specified above which constitutes a stable concentrated aqueous emulsion adaptable for the coating of llexible sheet packaging base .materials comprising a dispersion in about 40 parts by weight of water of about 60 parts by weight of a solution consistingessentially of (a) about 25 parts by volume of'di- Visobutyl adipate as a solvent, (b) about 2,5 parts by volume of glyceryl monostearate as an emulsifier, and i (c) about 10 parts by volume of a synergistic antioxidant combination of from 1 to 46 parts by weight of tertiary butyl-p-hydroxyanisole and fromV 9 to 4 parts by weight of 3,5ditertiarybutyl-p-hydroxytoluene.

Both BHA and BHT are solids at normal temperatures.

It is therefore necessary to dissolve the antioxidant com- 'bination of BHA and BHT in a common solvent prior to the formation of the above-described stable concentrated aqueous emulsion. It has been found that di-isobutyl adipate is admirably suited as a solvent for both of these T antioxidants. There are several other compounds which can also be employed as solvents for these two antioxidants, however,l none of them produce the overall advantageous solvent action of di-isobutyl adipate from a practical point of view. Such other less satisfactory solvents which are not included within the scope of our invention but which can be employedv less advanta- Ageously include butyl phthalyl butyl glycollate, various alkylaryl phosphates, dialkyl phthalates, variousY alkyl stearates, various alkyl adpates, propylene glycol mono laurate, glyceryl monooleate, etc.

The emulsifer designated for use in accordance with our invention has been found to be especially suitable for the particular purpose of producing a stable emulsion in both concentrated form and when the emulsion is subsequently greatly diluted. This emulsier is glyceryl monostearate. Numerous other emulsiers are also well known to the art and can be less advantageously emi ployed to produce emulsions of less satisfactory quality.

Such less advantageous emulsiers include arabic, gum tragacanth, glycol monolaurate, glyceryl mona .in the. hot di-isobutyl adipate solvent.

EXAMPLE I The following ingredients were employed to form the emulsion:

Ingredient: Vol. percent Di-i'sobutyl adipate 25 Butylated hydroxy toluene (BHT) 12.5 Butylated hydroxy anisole (BHA) 12.5 Glyceryl monostearate 10 Water 40 amounting to half the volume of this solvent and a similar quantity of BHT pelletswere then dissolved completely To this solution was then added the glyceryl monostearate emulsier.

The temperature was maintained at F. and the mixture was maintained in constant agitation. The indicated amount vof water was then violently agitated in 'a Premier dispensator (any similar agitator could be ernployed) at a temperature of about 76 F. The warm -solution of antioxidant and emulsifier was then slowly added to the agitating water. `Agitation was continued Vuntil most of the emulsion particles had reached a particular size of from 1 to 3 microns. yminutes although other apparatus could be used to speed This took about 30 this up. Less 4eiiicient apparatus could be used over a longer period of time. The product obtained was a heavy paste emulsion. This emulsion was found to be 'stable under all temperature conditions which would be vencountered during the transport of such a concentrated emulsion by common carrier to the locations where the emulsion would be employed for the treatment of paper. The finished concentrated paste emulsion was unaffected Aby light. However, it should be stored in air-tight cont'ainersV under conditions which are not permitted to be- -come excessively hot.

If a highly ecient agitator such as the Premier dispensator or similar agitator is not available the emulsion described in the above example can be prepared in any ordinary agitating device followed by passing the inter- -mediately dispersed material through an homogenizer or a colloid mill which produces emulsion particles of a size fromvabout 1 to about 3, microns.

Y EXAMPLE II V The procedure described in Example I was repeated Aexactlyexcept that the following portions were emi products. v v A apply wax .mixtures in .the liquid state at elevated tern.- peratures suchas those inthe rangeyof .150 F. to .220

. tion.

1 Other similar concentrated emulsions can be prepared f `llowing "the same procedure but employing variations 'theproportionof the ingredients. YOur invention 4is fnotspecically'restricted to the Aprecise proportions set v vforthbnt should not be allowed todeviate more "than a 4`'fewgptfercent from those designated. When itjis 'tofbeemj ployed for coating exible sheet .packaging materia1s,'the

emulsion 'can be V,diluted upto and evenmore thanflOO Vtir'nes with water employing ronly moderate care in ac- "complishing the dilution. The concentrated 'emulsion is quite stable at .100 to 1 dilutions. Thediluted vemulsions can be appliedto one or both surfaces of the paper or incorporated into .the paper through various means with ,which the industry is well acquainted. The `apparatus 'and techniques involved are wellA known to. those skilled .in .the Vart of manufacturing packaging materials.

l VWhen applying the antioxidant combination of this invention kto flexible packagingmaterials in the .form of a solution in a hydrocarbon wax, there is no need to 'resort to the use of aqueous emulsions ofthe type just l'described because .the antioxidant combination is'soluble in hydrocarbon waxes.` When a hot wax composition is applied .to flexible sheet packaging materials it can vbe solidified by permitting it to cool below 'the softenl material for the packaging material.' Paratiin and mix- '.tures thereof with various polymerized oleins and various fot'her Itypes of waxes as Well as variou-s blends of wax .have long'been used in the packagingindustry as coat- .ing materials for containers for the packaging ofy edible Most manufacturers of -packaging .materials F. At elevated temperatures, waxes tend to oxidize causing them to discolor, lose tensile-strength, produce offensive .odors, and otherwise'lose ltheir .most advanta- V v' genus physical and chemical properties. .Wa'xes which have been partially oxidized or have otherwise deteriorated during'the coating process have been. found to break down much faster when subjected to intense sunlight, the presence of metals and other conditions which tend to catalyze the oxidative condition.

Oxidation ofvarious waxes can be greatly'reduced by the addition of certain phenolicv types of antioxidantso knownfto those familiar with-the art. Prior to .our invention the introduction of antioxidants into waxes Tin V tended for use in packaging edibleproductscaused Athe hydrocarbon wax'compositions to eitherjdiscolor, develop "ia disagreeable odor, -or -to become otherwise unacceptable for food and' drug packaging; Although the question of toxicity is an important problem to. be overcome, it

is also essential that vtheY .packaging .materials have no disagreeable odors and that they have goodcolor.

According to this embodiment ofour invention; the:

use of the synergistic antioxidant combination described herein permits the formulation of hydrocarbon wax coating composition which has no odor attributable to the antioxidant combination and which is not associated with any deterioration of the color of the coating composi- Moreover, the coating composition contains nothing which is of questionable toxicity. Furthermore, Vthe antioxidant combination of this invention permits the preparation of coating compositions containing hydro- I carbon waxes which are more resistant to oxidation than fthe commercially available products now employed for this purpose. The following Vdata illustrates the advantages of our invention in providing stabilized wax cornpositions and packaging materials coated therewith.

.6' .EXAMPLE III were stabilized with kvarious concentrations of BHA, 5 BI-IIT and 50-50 combinations of the same. The wax vwas' stabilized Iby :heating to 170 FI, 'adding the solid antioxidant and then .agitating themixtnre. untilalllthe antioxidant was ctnnpletelydissolved,VU Stability `tests were then-madeonthe mixture .using -thestandard .300

1.0 F, AOLM test as described by Seubert; RALF... anidiAnidrW's, E. D., Antioxidant for waxes, Modern Packaging,-D`e

- sults were f obtained :V

- The eject of BHA andM-BH-Ton paran' "Hours Y- Synergiam Antioxidant Percent 'Stability f .(mh'oui's) `1163000511.: i 20. Y

Control "None l 8.752 BH `0:001 18:50 BHA. 03005U "31:6 BBA. 0.010-- 1 40.5 BHT- 0. 00 1v 15.0 BHT. 0.005 47.0 BHT...Y 0.010@ 69.3

BHA-|- BHT 000m-homos 28 BBM-BHT-.. 000254-00025 v8.8* .BBM-BHT.; 00054-0005 122.:3,

30 EXAM-PLE 1vV Samples of v-paraiiin wax 'containing 5 vpercent polyethylene were -stabilizedtwith .various vconcentrationsof BHA, BHT and combinations of v ypercent and .35..50percent `BHT 'in the manner 5described above; -This stabilized wax vwas. .coated onvegetable kparchment .paper kwitha laboratory l'roller to simula-te a cornrriercial wax-. Y

'ing applicator. Samples ofthewaxed parchment were tested for their stabilizing effect on lard using the Schaal 40. Oven method..r This method is describedfinthe .subject invention v.reportand by Bentz, R. W., Antioxidants for l Food. Papers, -Modern Packaging, vol. 2 7 (September 1953),' l141-143. y.The results Yareas follows: -f

45 The eject of stabilized :waxed parchment on lard);

Antioxidant; Y Percent Days `Stable Synergism at 145 F. r (in days) Control Control.l j 3 BHA l0. 0025 555' BHA... 0.005 Ao BHA.- 0. 010. `6. 5 BBA... 0.020 .127;5 -BHA 0 030 I8.5 BHA 0.040 9:5 BHA.-. 41,050.1 M102 I BHT 0.0025 f 5' BHT.- 0. 005' 6 BHT 0.010 a .'7 vBHT 0.020 s BHT 05030 '9.'5 BHT- 0. 04o r 1 1-- HT. 0.050 10.5 BHA-FBHT 0. (1025 f6. 5

BHAl-BHT 0..005." f '-7. 5 i BHA-l-BHT. 0. 010 Y 8. 5 BHA+BHT 0.020 9. 5 BHA-I-BHT. 0.030 12. 0 BEAM-BH t 0.040 12. 0 BEA-i-BHT 0.050 12.0

EXAMPLE v Samples of paraffin wax containing 5 percent polyl Samples of paraiiin .containing no polyethylene Hours Stability at 300 F.

Synergism Antioxidant Percent (in hours) BHA -l- BHT 130 29 The preceding tables include a column which" shows the degree of synergism (S) which is defined as: S=A-1/2(B|C) wherein A is the stability of paraffin containing the antioxidant combination of BHA-l-BHT, VB is the stability of parain containing BHA in quantities equal to that of A and C represents the stability of paran containing BHT in quantities equal to that of iA-7 The Schaal oven method referred to above is a modification of the usual Schaal oven test wherein paper is pla-ced in -jars and covered with the test material. test results tabulated above were obtained from the` stor- Vage of jars at 145 F., containing the lard and treated paper which was tested every twelve hours organoleptically for rancidit'y. The results are shown in days of stability -at 145 F.

As mentioned hereinabove the hydrocarbon waxes ern- Vployed can include various percentages of polyethylene and other alkylene polymers such aspolymerized isobutylenej It is ordinarily considered that the paraffin wax should constitute a fairly substantial proportion of the coating composition when applied to packaging materials. For the purposes of this invention we consider that the amount of parain or other mineral wax should constitute at least 10% of the total composition. This is based uponihe fact that the antioxidant combination with which this invention is concerned is not effective in a polymerized olefin such Vas' polyethylerie'."`AA

The coating materials with which this invention is concerned are especially advantageous for application to various grades of paper and paper board for the manufacture of butter and margarine'wrappers, containers for ice cream, milk, cheese, cottage cheese, etc., bags made from various grades of glassine paper for candy, pop corn,

potato chips, etc. Moreover, chip board coated with a Vstabilized hydrocarbon wax can be advantageously employed in the preparation of tubes, trays, etc. for the storage of edible products. Furthermore, various grades of gsillte, parchment and other papers can be used as liners andi foodcartons for numerous types of edible materials containing fatty constituents. Various kraft papers can also be coated with the wax compositions of this invention and fabricated into containers such as boxes and bags for edible materials such as animal feeds, fatty materials, etc. The materials which can be stored in the wrapping and packaging materials of this invention include inedible fatty and oily materials which tend to deteriorate by the formation of rancidity. Such ma- `terials are used in the paint industry and for other purposes. The materials which can be stored in the wrappers andfcontainers provided by our invention include animal, vegetable, fish and mineral oils, waxes, fats, greases and the like, e. g. lard, cottonseed oil, peanut oil, lariolin, mutton tallow and grease, beef tallow, white and yellow greases, linseed oil, cod liver oil, castor oil, olive oil, coconut oil, palm oil, corn oil, parain oil, carnauba wax, paraffin wax, beeswax, lard oil, sperm oil, transformer oils, citrus oils such as lemon oil, mono, diand triglycerides of various saturated and unsaturated fatty acids, hydrogenated fats and oils, etc., as well as materials containing a substantial proportion of any of the waxes, fats or oils, e. g. certain animal feeds, paint vehicles, furniture polishes, floor waxes, automobile polishes,

cottage cheese, milk, milk solids, powdered or whole parts by weight of water of about 60 parts by weight of The a solution consisting essentially of (a) about 20 parts of volume of di-isobutyl adipate as a solvent, (b) about 25 parts by volume of glyceryl monostearate as an emulsiier, and (c) about 10 parts by volume of a synergistic vantioxidant combination of from l to 6 parts by weight of tertiary butyl-p-hydroxyanisole and from 9 to 4 parts by weight of 3,5-ditertiary butyl-p-hydroxytoluene.

2. A composition as defined in claim 1 wherein the synergistic antioxidant combination consists of approximately equal quantities of the two constituents designated Vin (c).

References Cited in the file of this patent UNITED STATES PATENTS 691,952 Little Feb. 28, 1902 2,628,172 Jenett Feb. l0, 1953 2,658,004 Eldridge Nov. 3, 1953 2,658,835 Wymbs Nov. l0, 1953 2,704,746 Chenicek Mar. 22, 1955 2,715,073 Lowry Aug. 9, 1955 2,755,193 Rumberger July 17, 1956 FOREIGN PATENTS 621,923 Great Britain Apr. 22, 1949 658,168 Great Britain Dec. 3, 1952 685,168 Great Britain Dec. 31, 1952 

1. A STABLE CONCENTRATED AQUEOUS EMULSION ADAPTABLE FOR THE COATING OF FLEXIBLE SHEET PACAKAGING BASE MATERIALS CONSISTING ESSENTIALLY OF A DISPERSION IN ABOUT 40 PARTS BY WEIGHT OF WATER OF ABOUT 60 PARTS BY WEIGHT OF A SOLUTION CONSISTING ESSENTIALLY OF (A) ABOUT 20 PARTS OF VOLUME OF DI-ISOBUTYL ADIPATE AS A SOLVENT, (B) ABOUT 25 PARTS BY VOLUME OF GLYCERYL MONOSTEARATE AS AN EMULISIFER, AND (C) ABOUT 10 PARTS BY VOLUME OF A SYNERGISTIC ANTIOXIDANT COMBINATION OF FROM 1 TO 6 PARTS BY WEIGHT OF TERTIARY BUTY-P-HYDROXYANIOSLE AND FROM 9 TO 4 PARTS BY WEIGHT OF 3,5-DITERTIARY BUTYL-P-HYDROXYTOLUENE. 